According to one of the entries at www.merriam-webster.com/dictionary/key, a key is “a usually metal instrument by which the bolt of a lock is turned.” For purposes of this disclosure, such keys may be referred to as physical keys.
According to the WIKIPEDIA entry at en.wikipedia.org/wiki/Key (cryptography), in the field of cryptography, a key is “a piece of information (a parameter) that determines the functional output of a cryptographic algorithm or cipher.” For purposes of this disclosure, such keys may be referred to as digital keys.
Traditionally, physical keys have been used to control access to valuable, dangerous, or confidential possessions, such as houses, cars, and bank account statements. For instance, if a person wanted to protect sensitive documents from unauthorized viewing, that person could keep those documents in a locked file cabinet. Similarly, if a mother wanted to allow her son to use the mother's car, the mother could give the son a physical key to the car.
The present disclosure describes methods and apparatus for conveying a digital key or related information via physical contact, and for using such information to obtain access to protected resources. Such a system may be referred to as a touch key system.